A metal from group IVb of the periodic table is used as the target in a reactive deposition process. An inert gas such as argon is admitted within the chamber (12) housing the target (21). Electrical power at a constant level is supplied to the target, ionizing the inert gas so that the ions bombard the metal target and initiate sputtering. A controlled flow of a reactive gas such as nitrogen is then admitted to the chamber and controlled in such a way that the metal deposition rate is not lowered. The amount of the reactive gas is constantly sampled to provide a control signal used to regulate admission of the reactive gas at the proper rate for most effective deposition of the metal onto the substrate. Closed loop systems (45, 29, 31, 43, 44, 26, 27, 39, 62) regulate the level of electrical power supplied to the target, rate of admission of the inert gas, and rate of admission of the reactive gas.